Patent GB-932037-A (GB)
Title: Wheel tread brake unit for railway car trucks
IPC: B61H15/00
Filed: 1960-12-21
Abstract: 932,037. Shoe-brakes. WESTINGHOUSE AIR BRAKE CO. Dec. 21, 1960 [Dec. 31 1959], No. 43862/60. Class 103 (1). [Also in Group XXIV] Relative rocking movement of a casing comprising a brake cylinder and a lever connected to a piston and pivoted within the casing actuates two brake shoes, movably supported by one side frame of a rail car truck, to brake two wheels on the same side of the truck. A casing 18 is pivoted at 2 to a bracket 4 bolted to a side frame of a rail truck and is formed at the upper end as a brake cylinder 19. A piston 27 within the cylinder has an integral piston-rod 37 pivoted to one end of a lever 39, pivoted at 45 to the casing 18 and at its lower end at 55 to a brake rod 53 pivotally connected to brake hangers 16 and a brake shoe 10. An internally-threaded sleeve 84 is carried in a rectangular member 73 pivoted at 80 to the casing 18. A brake rod 86 is threaded in the sleeve 84 and actuates a lever 87 suspended from a pin 90 on a bracket 89 secured to the truck frame, a link 92 is connected to a pin 94 on the lever 87 and to a pin 97 connecting brake hangers 17 with brake shoes 12. When pneumatic pressure is applied through pipe 36 to space 34, the piston 27 moves to the right to turn lever 39 clockwise to apply the shoe 10 and the reaction on pivot 41 turns the casing 18 anti-clockwise about pivot 2 to apply the shoe 12 through rod 86, lever 87 and link 92. Manual application of the brakes may be made by tension in a cable 70 attached to the piston 27. To allow some lateral deflection, the pivots 2 and 59 are rubber mounted in the bracket 4. Adjustment.-A brake shoe spacing arrangement comprises a rod 93 pivoted at 94 to the lever 87 and slidable in a forked member 104 secured to the truck frame by an eyebolt 105. The member 104 has a rectangular opening 103 which contains a clutch mechanism, engaging the rod 93, comprising pawls 116, 117 pivoted on a slide member 115 and biased into frictional engagement with the rod 93 by a spring 130. An inner spring 131 acts to bias the member 115 to the left and also acts as a pull-off spring for the shoe 12. The clearance between the righthand end of the member 115 and the end wall 112 of the member 104 is related to the desired off-clearance of the shoe 12; if this clearance becomes excessive during application, the rod 93 will move through the pawls 116, 117 after the member 115 has reached its extreme rightward travel, and reposition the member 115 on the rod 93 to provide the desired clearance. Adjustment of the length of the rod 86, and thus the position of the shoe 10, is provided by rotation of the sleeve 84 through a pawl-and-ratchet mechanism 135, 134 connected by links 138, 144 and resilient link 148 to the brake rod 53. Excessive relative movement between the rod 53 and the easing 18, caused by wear on shoe 10, allows the pawl 135 to engage a tooth of the ratchet wheel 134 attached to the sleeve 84, and rotate the sleeve to reduce the brake shoe clearance. Manual adjustment may be made by application of a tool to a polyonal boss 85 on the sleeve 84, and by prising the pawls 116, 117 out of contact with the rod 93 by a screw-driver applied under a tongue 132.